Currently, there are four clinically-approved PARP1/2 inhibitors—olaparib (Lynparza®, Astra Zeneca), rucaparib (Rubraca®, Clovis), niraparib (Zejula®, Tesaro), and talazoparib (Talzenna®, Pfizer)—which, at least for now, are almost exclusively used for treating HR-deficient types of cancer or cancers that have responded well to previous therapy with platinum compounds [282,302]. Here, PARP1 is linked to cancer.